What hard disks does A/UX support

[Charlie C. Kim]

A Rodime 140 and theoretically the entire Rodime line should work just
fine as an A/UX only disk.  The A/UX generic SCSI driver seems to be
very good.  (The Rodmine 140 is slightly faster than the std. Apple
80MB internal).  Unfortunately, the Rodime drivers do not support the
Macintosh II partition manager as defined in Inside Macintosh Vol. V,
thus you cannot take a parition for use under MacOS - don't even try!
Actually, the Apple MacOS driver almost works--reads seem reliable,
but writing is not :-).  This is probably true of most MacOS disk
drivers today (of course, it's possible that with some of the disks,
the Apple MacOS SCSI disk driver would work, but not on the Rodime at
least).

Never run a SCSI driver that does not understand the IM Vol V notion
of partitions on a drive that is partitioned.  (You really have to
work at this though -- about the only way to get it on the disk is
using dd :-).  It will not work correctly.  Another warning, there is
another partition manager defined in Inside Macintosh Volume IV that
is quite different and incompatible with the one defined for macintosh
II's and used by A/UX.  (The sample SCSI driver from Apple deals with
IM.IV partitions).

The easiest way to setup a Rodime 140, is to just dd over the data
from a distribution 80MB and munge with the partition tables to get
the extra 60 meg in.  To play things really safe, either kill the
MacOS partition or lock it with dp--leaving it around unlocked can
cause problems.

My advice is to keep the changes as simple as possible.  I simply
turned off writes on the MacOS partition (with a copy of sash and
utilities) and reused the "Extra" partition at DPM 8 as a "user UFS
partition" containing the remainder of the space (physical:
125218 at 156368).  However, this does have one minor problem.  Disk
partitions/slices under A/UX (e.g. /dev/dsk/c0d0s0, s1, s2) are not
"directly" mapped to the partitions under the partitition manager.
You use "pname" to define mappings -- so be careful there.  You might
find it simpler in the long run to simply shuffle around the file
systems so that you can have one big A/UX partition--however, the
problem here is knowing where to put things.  The eschatology file
system are presumably placed on the disk in different physical
locations to minimize the effects of any hardware disk damage (of
course, this didn't help me any -- my disk just went under totally).

If you don't think you want to copy the entire disk and just want to
get things to the point where you can munge things around, the
physical disk layout is something like:
	<boot block>
	<partition blocks> [1 per partition]
	<MAC OS driver>
	<1st extra/Free parition>..
just dd from 0 to the physical partition start of the first partition
following the MacOS driver.  I am pretty sure the dp size blocks are
512byte units, so you could setup for running dp on a new disk by
issuing the command "dd if=/dev/dsk/cXd0s31 of=/dev/dsk/cYd0s31
count=96" where X is the SCSI id of the original and Y of the
destination.  This will copy the MacOS driver too.  This is just
paranoia because I'm not sure what MacOS will do if it sees
a disk drive without a 'driver' on it.

In article <3920 at sphinx.uchicago.edu> sas1 at sphinx.uchicago.edu.UUCP (Stuart Schmukler) writes:
>In prinicple the 'dp' utility can deal with any type of hard drive.
>The problems are:
>	Configuring and loading the Eschatology parts of A/UX
>	Loading the Eschatology parts of A/UX
>	Configuring the Mac partition
>	Loading the Mac partition
>and	making sure that the Mac OS respects the partition 
>	 (say during Erase Disk)
>
>SaS
>
>PS: Dealing with 'dp' is arcane. If I was clearer on the subject I'd
>write it up. We found that you had to check the System Admin man pages
>and the A/UX device drivers manual.

The easiest way to deal with these problems (as noted above) is to
duplicate the partitions from the distribution disk and play with
them.  The only problem left is ensuring that MacOS respects the
partitions: it should if the MacOS driver you installed respects the
Macintosh II disk partition manager.  If it does not, then it will
probably smash the disk anyway.

I think the idea was to have the partitions generated from MacOS by a
vendor specific utility that reserves space for <n> (user specified)
partitions, creates any MacOS partitions you wanted, and installs the
driver.  dp could then be used to install the A/UX partitions.  Of
course, the problem is finding disk drivers that support the Mac II
partition manager.  Remember, it is important to note "dp" can't be
expected to initialize the disk correctly for MacOS because a vendor
specific driver must be installed if you are to use it under MacOS.

Suggestion for the next release of A/UX -- either make it easier to
build the default set of partitions (including MacOS partitions) via
dp or leave more slots in the standard distribution!  There's only two
free partitions--for really big drives, this really isn't enough.

Also, make the slice to partition mapping go in order or have some
more rigid mapping.  This would make me feel much safer.


Charlie C. Kim
User Services
Columbia University